280 Schermerhorn—Northern and Northwestern Lakes. 
Maine to the isthmus of Panama, if the distance be measured 
2. 
iF, 
| 
iS 
NN 
SP) 
| 
arenes 
an 
fel 
— 
ae 
c La kK el Lchil 
of the Lakes 
Longitudinal 
sections 
on the tine af deepest water. 
along the veneral contour 
of the coast, ignoring minor 
indentations. 
The recently perfected 
levels of the U. 8. Lake 
Surveys, between tide water 
and the lakes, fixes the ele- 
vation of their mean sur- 
faces above mean sea level 
as follows: 
Lake. Feet. 
Ontario== =e 246% 
Hire 002 aa 57285 
Huron and Michigan___ 581;3) 
Superionsis aye lee 60145 
(See fig. 2.) 
The difference of 204 feet 
between Lakes Superior and 
Huron occurs in the rapids 
of St. Mary’s River; the 
8,4, feet between Lakes 
Huron and Hrie mainly in 
Detroit River. 
The difference of 326 feet 
between lakes Hrie and 
Ontario occurs in the vicin- 
| ity of Niagara Falls and is 
principally assembled as fol- 
lows (see fig. 3): 100 feet in 
the five miles of rapids be- 
tween ‘Lewiston and the 
lower Suspension Bridge, 
10 feet in the rapids be- 
tween the Bridge and the 
Falls, 160 feet at the Falls,* 
50 feet in the rapids imme- 
diately above the Falls, and 
6 feet in the upper Niagara 
River. 
The mean depth of Lake 
Superior is about 475 feet; 
the deepest point (see fig. 2) 
marks a depth of 1008 feet, 
or over 406 feet below the 
level of the sea. Lake 
* The height of the Falls is 155 feet on the Canadian side, 161 feet near the 
site of Terrapin Tower and 169 feet near the east side of the American Falls. 
